St Mochta's

Hartstown/Huntstown are the club's rivals, and the fixture between them goes by two names: the "Mochta's derby" and the "Dublin 15 derby".

St Mochta's began inside a parish society. In September 1949 Barth O'Brien proposed to the St. Mochta's branch of the Catholic Young Men's Society (CYMS) that it start a football section. The members voted on the code and chose association football over rugby and Gaelic football. For the first match the club borrowed the navy and sky blue of the Castleknock College rugby jersey, and it has worn those colours since. The parent branch folded in 1962, and the club carried on alone under the same name.

The early years were unsettled: pitches at Somerton, where Castleknock GAA now plays, and briefly at Coolmine Lane. Then came Porterstown Road, and the club has not moved since.

The recent honours come from the Leinster Senior League. The Saints won its Senior Division in 2016–17, again in 2022–23, and once more in 2024–25. In between, in 2020, they beat Killester Donnycarney 2–1 to take the FAI Intermediate Cup. In 2023–24 they lost the Leinster Senior Cup final 3–1 to St Patrick's Athletic. A partnership with Shelbourne FC followed in 2022.

Players have come through the club and gone on to English sides. Mark Kennedy, a Republic of Ireland international, played for Manchester City, Liverpool and Wolves. Academy products today include Tayo Adamarole at Crystal Palace and David Okagbue at Stoke City. When the club marked its 70th anniversary in 2019, it invited Bristol Rovers for a friendly and lost 7–0.

Porterstown Road in Clonsilla holds 600 people, with room on paper for 2,000. That is the ground where the Dublin 15 derby is played.